Fractionation, structure and conformation characterization of polysaccharides from Anoectochilus roxburghii

Two new isolated polysaccharides, ARPP-40 (40 % ethanol precipitate) and ARPP-70 (70 % ethanol precipitate), were extracted from Anoectochilus roxburghii. The physicochemical properties of two polysaccharides were analyzed and the results showed the relative weight average molecular weights and contents of neutral sugar for ARPP-40 and ARPP-70 were 423 kDa and 97.4 %, 10.8 kDa and 51.4 %, respectively. In terms of monosaccharide composition, ARPP-40 contained only glucose, while ARPP-70 was composed of seven monosaccharides, of which glucose and galactose were the main components. Furthermore, the structure and conformation characteristics of ARPP-40 were systematically investigated. The results revealed that ARPP-40 was supposed to be a glucan and existed as a flexible chain with a polydispersity index of 1.02 in 0.1 M NaNO3 solution. The systematic information on structural and conformational properties of ARPP-40 was meaningful for its further application in food and medicinal industry.